32 E. E. JUST. 



(c) Precipitation of the Hetero-agglutinin by Echinarachnius 

 Sperm. Thirdly, it can be shown that the agglutinin for Echi- 

 naraclinius sperm present in sea-water above Arbacia eggs can 

 be precipitated by Echinarachnius sperm leaving the Arbacia 

 sperm agglutinin practically undiminished in strength. Thus, 

 on July 15, I prepared three vials each with I c.c. of filtered 

 Arbacia egg-water; to these vials, A, B, and C respectively were 

 added I, 2 and 4 drops of Echinarachnius sperm suspension. 

 A fourth vial, D (control), contained 5 c.c. of Arbacia egg- water 

 with no sperm. After five minutes the following results on 

 Echinarachnius sperm were recorded: A, powerful agglutinant 

 undiluted; negative at 1/8 dilution; B, positive; C, positive. 



After ten minutes, C was negative; after fifteen B faintly 

 positive; at twenty minutes all vials were negative. 



Tested on Arbacia sperm, the vials A, B and D (control) gave 

 a 6-second reaction at 1/400 dilution. 



This experiment when repeated gave essentially the same 

 results: the Echinarachnius sperm agglutinin may be completely 

 removed, although this removal is not immediate, the rapidity 

 with which the hetero-agglutinin is destroyed depending upon 

 the density of the Echinarachnius sperm suspension used; the 

 iso-agglutinin, on the other hand, remains undiminished in 

 power. 



(d} Agglutinative Action of Arbacia Blood on Echinarachnius 

 Sperm. Farther, it can be demonstrated that the perivisceral 

 fluid of Arbacia has ait agglutinative action on Echinarachnius 

 sperm though lacking this action on Arbacia sperm. Thus on 

 July 17, I carefully collected blood from four Arbacia which after 

 clotting was filtered. Ten determinations on Arbacia sperm 

 were negative in each case, the sperm showing, however, un- 

 diminished response to Arbacia egg- water tested after each trial 

 with the blood. This perivisceral fluid agglutinated sperm from 

 six Echinarachnius tested in turn. 



Frequently, as in another observation on this same day, July 

 17, females were found whose blood was negative to both Arbacia 

 and Echinarachnius sperm. Blood is positive with Arbacia sperm 

 if the ovaries are ruptured when the animals are opened. Ex- 

 treme care is necessary to avoid this. 



